Electric weft detecting system for looms



Nqv. 25', 1947. v. F. SEPAVICH sf AL 2,431,650

ELECTRIC WEFT DETECTING SYSTEM FOR LOOMS Filed Jun 6, 1946 T; L y 45%42 l l 1 v I INIVENTORS VICTOR F. .SEPAV/CH JOHN C. MANOOG ATTORNEY Patented Nov. 25, 1947 ELECTRIC WEFT DETECTING SYSTEM FOR LOOMS Victor F. Sepavich and John C. Manoog, Worcestar, Mass., assignors to Crompton & Knowles Loom Works, Worcester, Mass, a corporation of Massachusetts Application June 6, 1946, Serial No. 674,920

'1 Claims.

This invention relates to electrical weft detecting systems for looms and it is the general object of the invention to provide such a system operating preferably with direct current and employing a gas filled electronic tube.

Weft detectors are generally located in front of the loom lay and have a brief contact with the bobbin as the lay is on its front center position. When the usual type of solenoid is used to control loom operation sufiicient time must be allowed for its effective energization and this time generally determines the interval during which the detector must have contact with the bobbin. When weaving very fine weft it is desirable that the interval of detector contact be shorter than that ordinarily required for the energization of the solenoid.

We have already proposed an electronic Weft detecting system in which the detector upon indication of weft exhaustion closes a signaling circuit which alters the electric condition of the grid of an electronic tube. That system operates with alternating current so that the plate within the tube was alternately positive and negative. The tube can transmit current only when the plate is positive. If the detector closes the signaling circuit during a negative alternation only no current can fiow for the excitation of the solenoid, and even though the detector contact be closed during a positive alternation the latter is too short to actuate the solenoid. When using alternating current it is desirable to provide some means for prolonging the detector control of the tube grid, as by a condenser. Furthermore, it is desirable to provide for energization of the relay or solenoid when the tube plate is negative, or after tube current ceases, and this may also be effected by condensers.

It is an important object of our present invention to provide an electronic weft detecting circuit with a gas filled tube and operate it by direct current. Once a tube of this type is fired flow of current through it is continued by the direct current and the previously mentioned condensers ar unnecessary. It is necessary of course to interrupt the plate circuit after the solenoid has initiated the desired change in loom operation, and this result can be accomplished in any one of several ways, as by periodic opening of the circuit due to a moving part of the loom, or by a switch which is opened on complete energization of the solenoid. We illustrate this latter method of control, but wish it to be understood that our invention is not limited to such a control.

It is a further object of our invention to operate 2 the detector or signal circuit by a low voltage source of electric power and isolate it from the higher voltage plate circuit, thereby avoiding all danger of shock to the weaver.

With these and other objects in view which will appear as the description proceeds, our invention resides in the combination and arrangement of parts hereinafter described and set forth.

In the accompanying drawings, wherein a convenient embodiment of our invention is set forth,

Fig. 1 is a, plan view partly in section of a weft detector of th electrical type and a depleted bobbin, and

Fig. 2 is a diagrammatic view of the electric circuits used with our invention.

Referring particularly to Fig. 1, we have shown a stationary loom carried support ll)v on which is mounted the detector D made with a body of insulating material designated at l l. The detector is bolted as at I2 to the support Ill and has slidably mounted therein right and left hand electric conducting detector fingers l3 and I4, respectively, adapted for engagement at their rear ends with the ferrule l5 of a bobbin B when the latter is depleted of weft. Small springs l6 urge the detector fingers rearwardly but permit them to move forwardly. The fingers slide through electric current conducting bearings I1 and I8, provided, respectively, for the right and left fingers, and these bearings are connected electrically to wires I9 and 20.

Under normal weaving conditions when sufficient weft is present during the detecting interval it will strike the fingers l3 and I4 and move them forwardly without connecting them electrically. When the weft is depleted, however, the ferrule electrically connects the fingers and wires [9 and 20. The body I I, while made of insulating material, can be considered also as having a very high resistance.

Indication of weft exhaustion by the detector initiates a change in m operation, such as stoppage or replenishment, by means of solenoid S shown in Fig. 2. Two power lines L and L supply alternating current preferably though not necessarily of a voltage usually found in lighting circuits. The solenoid is controlled through a relay 25 which when energized closes a switch 26. The latter switch is normally open and the solenoid deenergized, but when the relay 25 is excited it closes a switch 26, whereupon current flows in the following solenoid circuit: line wire L, wire 21, switch 26, wire 28, solenoid S, and wire 29 back to wire L. Closure of this circuit causes the solenoid to lift its core 30 which can be utilized to initiat a change in loom operation. It is not thought necessary to indicate how movement of the core initiates these changes.

The electronic circuit includes a gas filled electronic tube 35 having a plate 36, a cathode 31, a control grid 38, and preferably a shield grid 39. The filament 46 serves to heat the cathode and is supplied with alternating current derived from.

the secondary 4| of a transformer T the primary d2 of which is connected across the lines L and L by wires 43 and 44, respectively. The filament circuit is as follows: primary 4|, wire 45, resis tance 46, filament 40, wire 41 and wire 48 back to the secondary 4|. This filament circuit is closed during loom operation so that the cathode will always be in readiness to effect flow of current through the tube when such flow is permitted by the grid 38.

In order to provide the direct current needed for the operation of our present invention we utilize two rectifiers one of which is for the detector and grid circuit and the other of which is for the relay circuit. The detector circuit rectifier 56 is supplied with power from the secondary 4| by the following circuit: secondary 4 I, wire 45, wire 5|. rectifier 5!], Wire 52, and wire 48 back to the secondary 4|. The rectifier 50 is thus permanently connected to the transformer T and Whenever the lines L and L are alive the rectifier will serve as a source of low voltage direct current. We find in some instances that it is desirable that the rectifier 5!] supply a higher voltage than is desirable for the filament and it is for. this reason that we use the resistance 46 in the fila ment circuit. The latter resistance should be capable of carrying the filament current but need not have very high ohmic value.

The detector circuit including the rectifier 50 is as follows: the positive side of rectifier 50, wire 55, ground, up from ground to wire |9, detector D, wire 20, junction 56, resistance 51 and wire 58 to the negative side of the rectifier 50. Th grid 38 is connected to the junction 56 by wire 59. This detector circuit is normally open or at least in such condition that the grid can prevent flow of current through the tube 35. When the detector indicates weft exhaustion, however, current will flow momentarily through the detector circuit and the potential of the junction 56 and the grid 38 will be altered in such megnner that electric current can flow through the tu e.

The relay circuit is supplied by the second i rectifier 6|] which provides a higher source of Voltage than does rectifier 50. The second rectifier is connected by wires 6| and 62 to the power lines L and L, respectively, and is therefore a source of constantly available direct current whenever lines L and L are alive. When the rid permits flow of current through the tube the following relay circuit is closed: the positive side of rectifier 60, wire 65, switch 66 (normally closed). wire 61, relay 25, wire 68. plate 36 through the tube to cathode 31, wires 69 and 16 to the ground, and then up from the ground by wire H to the negative side of the rectifier 66.

The tube 35 is of the gas filled type and When once fired by closure of the detector circuit will continue to fire or pass current after opening of the detector circuit. Restoration of grid 38 to its normal inhibitory condition upon opening of the detector circuit does not stop flow of current through the tube 35. It is necessary, therefore, to open the relay circuit after the solenoid has completed its function of initiating a change in loom operation, and to accomplish this result We place the switch 66 under control of the core 30 as indicated diagrammatically in Fig. 2. Whenever the solenoid is fully energized movement of its core will open the switch 66 and thereby interrupt the relay circuit through the tube. The

7 tube has a very low deionization period so that a brief opening of the switch 66 is sufiicient to restore the tube to its normal non-conducting condition, and return of switch 66 to its normally closed condition will not again reestablish flow of current through the tube if the grid is in its normal position. It Will be seen by an inspection of Fig. 2 that it is not necessary to use condensers or any similar electric devices for storing a charge electricity, inasmuch as firing of the tube, once initiated by a brief closure of the detector circuit, will continue because of ionization within the tube.

We have shown rectifiers 56 and 60 as sources of direct current powered by an alternating current, and have in practice used the so-called dry plate or disk rectifiers. We do not wish, however, to be limited to this particular kind of source of direct current. It is ordinarily desirable that the plate circuit be energized by a source of power having a higher voltage than that needed for the detector circuit, and it is for this reason that we have shown two rectifiers, but We are not limited to the use of two rectifiers.

From the foregoing it will be seen that we have provided a simple form of electronic weft detector circuit operating with direct current and utilizing a gas filled electronic tube. A very brief contact of the bobbin ferrule with the detector fingers will suffice to fire the tube, and after the tube has been fired it will continue to fire and permit current to flow through the relay after the detector circuit has been opened. In order to interrupt the relay circuit after its function has been effectively performed we open the switch 66 by the solenoid. As already indicated, however, this is only one method by which the relay circuit can be opened to efiect deionization of of the tube after the solenoid has been effectively energized, and We do not Wish to be limited to this method. Furthermore, the detector circuit operates at low voltage and is in effect isolated from the higher voltage relay circuit.

Having thus described our invention it will be seen that changes and modifications may be made therein by those skilled in the art Without departing from the spirit and scope of the invention and we do not Wish to be limited to the details herein disclosed, but what We claim is:

1. In an electric weft detectin system for a loom having an electromagnetic device which when effectively energized causes a change in loom operation, an electric Weft detector having two electrodes which are electrically connected to each other for a given interval of time when the detector indicates Weft exhaustion, an electronic tube containing gasand having a control grid, a source of direct current electric power, electric circuit means including said source, tube and device normally tending to energize the device but normally restrained from doing so by the grid, detector circuit means connected to the grid and effective when said electrodes are in electric contact to alter the grid and thereby enable said electric circuit means to energize said device effectively by electric current flowing through the tube for a period continuing beyond said interval, and means to open said electric circuit means subsequent to effective energi-zation of said device. V

r 2, In an electric Weft detecting system for a loom having an electromagnetic device which when effectively energized causes a change i loom operation, an electric weft detector having two electrodes Which areelectrically connected to each other for a given interval of time when the detector indicates weft exhaustion, an electronic tube containing gas and having a control grid normally capable of preventing flow of electric current through the tube, a source of direct current electric power, electric circuit means including said source, tube and device normally prevented from effectively energizing the latter due to the normal condition of the grid, electric means effective upon contact of said electrodes to alter the electric condition of the grid and enable said electric circuit means effectively to energize said device, and means thereafter operative to open said electric circuit means, said tube effective to transmit current from said source for the energization of the device from the time the electric condition of the grid is altered and subsequent to said interval and until said electric circuit means is opened.

3. In an electric weft detecting system for a loom having an electromagnetic device which when effectively energized causes a change in loom operation, an electric weft detector havin two electrodes which are electrically connected to each other for a given interval of time when the detector indicates weft exhaustion, an electronic tube containing gas and having a control grid, a source of direct current electric power, electric circuit means including said source, tube and device, a second source of direct current electric power, a detector circuit including said second source and detector connected to the grid and normally enabling the latter to prevent flow of current through the tube when said electrodes are electrically disconnected, said detector circuit effective upon contact with said electrodes to alter the grid and enable current from the first source of flow through said tube, said current due to the nature of the tube continuing to flow subsequent to said interval to cause effective energization of said device, and means to open said electric circuit means to interrupt flow of current through the tube and effect the deenergization of said device.

4. In an electric weft detecting system foraloom having an electromagnetic device which when effectively energized causes a change in loom operation, an electric weft detector having two electrodes which are electrically connected to each other for a given interval of time when the detector indicates weft exhaustion, an electronic tube having a control grid, plate and cathode and containing gas, a source of direct current electric power connected in circuit with said plate and cathode and device and normally tending to cause current to pass between the plate and cathode to energize the device but prevented from doing so by the grid when the latter is in normal condition, a detector circuit connected to the grid and effective when said electrodes are electrically disconnected to maintain the grid in normal condition but effective when said electrodes are in electric contact during said interval to alter the grid and thereby enable current to flow from the plate to the cathode through said tube to cause effective energization of said device, the gas within the tube continuing to ionize subsequent to said interval to effect continued energiz'ation of said devi e, and means effective to interrupt ionization of gas within the tube subsequent to effective energiz'ation of said device.

5.- In an electric weft detecting system for a loom having an electromagnetic device which when effectively energized causes a change in loom operation, an electric weft detector having two electrodes which are electrically connected to each other when the detector indicates weft exhaustion, a source of relatively high voltage direct current, a second source of relatively low voltage direct current, a gas filled electronic tube normally incapable of conducting electric current, electric circuit means including the tube and device and powered by said first source, and

additional electric circuit means powered by the second source and effective upon contact of said electrodes to enable said tube to conduct current in the first circuit means for the effective energization of said device.

6. In an electric weft detecting system for a loom having an electromagnetic device which when effectivel energized causes a change in loom operation, an electric weft detector having two electrodes which are electrically connected to each other for a given interval of time when the detector indicates weft exhaustion, a source of relatively high voltage direct current, a second source of relatively low voltage direct current, a gas filled electronic tube having a grid, electric circuit means powered by the first source and including the tube and device normally prevented from energizing the latter when the grid is in normal condition but enabled to energize the device when the grid is in abnormal condition, and detector circuit means isolated from the first circuit means powered by the second source and maintaining the grid at normal condition when said electrodes are out of contact with each other but creating an abnormal condition in said grid enabling current to flow through the tube when said electrodes are in contact with each other, ionization occurring within the tube when the grid assumes the abnormal condition thereof and continuing subsequent to said interval to cause effective energization of said device, and means to interrupt ionization within the tube after said device has been effectively energized.

7. In an electric weft detecting system for a loom having an electromagnetic device which when effectively energized causes a change in loom operation, an electric weft detector having two electrodes which are electrically connected to each other for a given interval of time when the detector indicates weft exhaustion, a source of relatively high voltage alternating current, a transformer powered by said source and providing a relatively low voltage alternating current, an electronic tube having a grid and filament and containing gas, a rectifier powered by said transformer and providing a source of relatively low voltage direct current, a second rectifier powered by the first named source and providing a source of relatively high voltage direct current, electric means connecting the filament to the transformer, electric circuit means containing the third source, tube and device prevented from energizing the latter when the grid is in normal condition, detector circuit means including the second source and detector connected to the grid and maintaining the latter in normal condition when said electrodes are electrically disconnected, said detecting circuit upon electric engagement of the electrodes altering the grid to enable current to flow through the tube for the NIT effective .energization of the device, and means U ED STATES PATENTS effective subsequent to said interval and effective Number Name Date energization of the device to arrest ionization 4 ,6 1 Young Feb. 7, 1939 within the tube. 5 ,3 6, 40 Thomas Apr. 11, 1944 VICTOR F, SEPAVICH, 2,377,102 Payne May 29, 1945 JOHN MANOOG- FOREIGN PATENTS REFERENCES CITED Number Country Date The following references are of record in the m 400132 Great Bntam 1933 file of this patent: 

